Alliances

Whats the protocol on this in single person matches, do you announce your intention to ally and then you can ally or do you need a turns grace etc.
I am playing with a friend and others and was chatting in MSN the option to ally came up but we decided against it because it just didn't seem sporting. But with a game where we were getting annhilated would it have been ok to ally?
Tals
I am playing with a friend and others and was chatting in MSN the option to ally came up but we decided against it because it just didn't seem sporting. But with a game where we were getting annhilated would it have been ok to ally?
Tals